Suppose one wants to know who is the Prime Minister of Australia. If he asks this to someone we say "he enquired about Australian Prime Minister". Now, if someone tells him this info without asking, still he needs to open his ear and listen to it. But we never say "he enquired" here.

In similar way, (c) is wrong :) In very concrete sense it is correct. But we have to be at the right level of abstraction- when someone asks what happens inside CPU we shouldn't say 0's and 1's interchange each other ;)

please comment about loop instruction point, I understand that if loop instructions cannot be interrupted then infinite loops may result. But is this correct reasoning for this option to be false? Can you please give me some more details? Or should I go and read some good book on microprocessors too. I read Douglas Hall for 8086 in my college days, just want to avoid that now. How exactly loop instructions are processed?